P&W sees GTF architecture as viable for nextgen widebodies

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Pratt & Whitney (P&W) has not found any thrust limitations to its geared turbofan engine architecture, and believes its design is capable of powering the next generation of widebody aircraft, including Boeing's replacement for the 777 if such an aircraft is pursued.

The manufacturer's PW1000G has already been selected by Bombardier to power the 110/130-seat CSeries and by Mitsubishi to power the Mitsubishi Regional Jet (MRJ).

The CSeries will be powered with the 20,000lb-24,000lb thrust class PW1000G, designated the PW1500G, while the MRJ will be powered with the PW1200G, which offers thrust between 13,000lb and 17,000lb.

P&W's initial product definition for its geared engine architecture represents a technology level that is targeted to a 2013 entry-into-service for both the CSeries and MRJ.

However, late last year the company launched its second phase of technology development, which is really targeted for aircraft that will enter service in the 2015-2020 time period.

"Our objective, our goal is to improve fuel consumption in the order of 1% to 1.5% per year for each year of time. So if we were to go from 2013 to 2018, we have set a target to have fuel reduction in 8%-10% step change or improvement regime," P&W vice-president next generation product family Bob Saia told consultancy Innovation Analysis Group (IAG) in an exclusive interview that aired on 6 May.

With regard to power, there are "some basic fundamental elements associated with higher thrust that we're developing for a 30,000lb thrust class or even a 35,000lb thrust class so as Boeing and Airbus look at their next generation products and as they define requirements which we know will drive higher thrust, we will be able to add incremental benefit for our geared architecture at that higher thrust".

However, P&W has "tested up to 40,000lb of thrust, and we've run the test up to that level to ensure that we cleared any thrust requirement for this next generation of aircraft that will operate up to about 250 passengers", says Saia.

A 40,000lb thrust engine is capable of powering an aircraft like the Boeing 757, which requires 37,000lb to 38,000lb of thrust, notes Saia. "So we have covered that type of thrust requirement."

To date, however, P&W has not found any thrust limitations "that would prevent us from using this geared architecture to even a twin-engined, long-range aircraft like a Boeing 777 or an Airbus A350".

P&W is not targeting the A350. And the reason for that, says Saia, is that "if you wanted to really optimize the gear, you'd really like to start with a brand new paper airplane at the same time so then you have the ability to optimize both the aircraft, the structure, the positioning of the engine, and the engine design all in that design phase".

If, for example, a replacement aircraft was being designed for today's Boeing 777 "then certainly we believe a geared architecture would be a very viable offering for that kind of airplane", says Saia.

P&W does not rule out installing a geared engine on existing aircraft if the aircraft is expected to be in production for another five to ten years. But Saia points out that the business economics don't fully support re-engining aged aircraft versus a re-fresh of a production variant because re-engining involves adding a new nacelle and a new pylon, in addition to a new engine.

He adds: "We believe that as we evolve and get more testing under these early programmes that we've launched that we will have the ability of installing a geared architecture in a next generation widebody aircraft that would happen post-2018, 2020 so it would not be any of the aircraft certainly either being designed or in service today."